Master of Science in Civil Engineering (MSCE)


Civil and Environmental Engineering

Document Type



The increase in the global demand for fish feed in the last decades has resulted in the over exploitation of natural resources to produce more fishmeal supplies for aquaculture industry. The supply issues and high prices of fishmeal products have raised the incentives to seek for suitable alternatives to replace fishmeal protein. As a by-product of biofuel production process, residual microalgal biomass may be a low cost feed ingredient to the aquaculture diet. The potential of the use of a post lipid extraction Chlorella vulgaris/Leptolyngbya sp. Co-Culture (Louisiana co-culture) as a protein source in aquaculture feeds could help offset fishmeal. The objective of this research was to (1) Determine the effect of nutritional and environmental conditions on the Louisiana Co-Culture biochemical composition (2) determine whether the Louisiana co-culture contains the quality and quantity of amino acid profile to be used for aquaculture feed (3) determine the change in the protein content and amino acid profile of the Louisiana co-culture due to the system dilution rate and lipid extraction process (4) determine the cost savings as the residual microalgal biomass incorporates in the aquatic animal diets. The optimum growth condition for the Louisiana co-culture to obtain the highest lipid and protein contents was found at 25°C when the cultures were supplied with 40 mg N L-1 and 530 mg C L-1. The protein and lipid content of the Louisiana co-culture were determined at 26.5±4.39 and 37.3±0.60 percent, respectively on a dry mass basis. The quality of the protein (amino acid profile) of the Louisiana co-culture was not found a function of the lipid extraction process (Chloroform: methanol, 2:1 v/v) although the protein content was affected significantly. The protein content was lower in the residual microalgal biomass. From the theoretical stand point, the Louisiana co-culture can replace up to 41, 6.5, 51, and 7.4 percent of fishmeal protein in the diets of channel catfish (Ictalurus punctatus), chinook salmon (Oncorhynchus tshawytscha), hybrid striped sea bass (Morone chrysops× Morone saxatilis), and tiger prawn (Penaeus monodon), respectively which will result in a decrease of up to 16, 8.9,37, and 4.5 percent of the costs of their dietary proteins.



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Committee Chair

Rusch, Kelly A.